Vast amounts of information are provided on Web pages of the Internet. Many of the Web pages are described in a markup language, such as HTML. Source files in HTML are browsed by an application program called a browser.
Each Web page generally includes various pieces of information other than those required by the user. For browsing only required pieces of information, editing an existing source file is required. The markup language requires description according to the preset grammatical construction, so that the user without expertise of the markup language has difficulties in editing the source file.
This problem is not restricted to Web pages in HTML provided on the Internet but is commonly found in source files, which are described in various markup languages.